Aromatic polyamide, optical anisotropic dope and articles and preparation for the same

Abstract

The present invention is directed to an aromatic polyamide of formula (I), ##STR1## an optical anisotropic dope containing the aromatic polyamide and a process of making the optical anisotropic dope which does not require sulfuric acid. R is an unsubstituted aromatic group or an aromatic group having at least one nitrile group substituted on the aromatic nucleus, with the proviso that at least 25 mol % of R in the aromatic polyamide is an aromatic group having at least one nitrile group substituted on the aromatic nucleus; R' is phenyl, naphthyl or diphenyl, which is unsubstituted or substituted with Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms; and n is an integer between 10 and 100,000.

What is claimed is: 
     
       1. An aromatic polyamide of formula (I) ##STR12## wherein R is an aromatic group having a nitrile group substituted on the aromatic nucleus or an aromatic group that does not have a nitrile group substituted on the aromatic nucleus, where at least 25 mol % of R is an aromatic group having a nitrile group substituted on the aromatic nucleus; R' is phenyl, napthyl or diphenyl, which is unsubstituted or substituted with Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms; and   n is an integer between 10 and 100,000.   
     
     
       2. The aromatic polyamide of claim 1, wherein an absorption band of said nitrile group is shown at 2230 cm -1  in an infrared spectrum. 
     
     
       3. The aromatic polyamide of claim 1, wherein R is selected from the group consisting of: ##STR13## wherein Y is Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms. 
     
     
       4. The aromatic polyamide of claim 1, wherein 100 mol % of R is an aromatic group having a nitrile group substituted on the aromatic nucleus. 
     
     
       5. The aromatic polyamide of claim 1, which is soluble in a polar organic solvent containing an inorganic salt. 
     
     
       6. The aromatic polyamide of claim 1, which has an intrinsic viscosity of at least 2.0. 
     
     
       7. An anisotropic polyamide dope, comprising: (a) an aromatic polyamide of formula (I) ##STR14##  wherein R is an aromatic group having a nitrile group substituted on the aromatic nucleus or an aromatic group that does not have a nitrile group substituted on the aromatic nucleus, where at least 25 mol % of R is an aromatic group a having a nitrile group substituted on the aromatic nucleus;   R' is phenyl, napthyl or diphenyl, which is unsubstituted or substituted with Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms; and   n is an integer between 10 and 100,000; (b) a polar organic solvent; and   (c) an inorganic salt;     wherein the dope contains at least 7% by weight of said aromatic polyamide and at least 1% by weight of said inorganic salt.   
     
     
       8. The anisotropic polyamide dope of claim 7, wherein R is selected from the group consisting of ##STR15## wherein Y is Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms. 
     
     
       9. The anisotropic polyamide dope of claim 7, wherein 100 mol % of said R is an aromatic group having a nitrile group substituted on the aromatic nucleus. 
     
     
       10. The anisotropic polyamide dope of claim 7, wherein said aromatic polyamide has an intrinsic viscosity of at least 2.0. 
     
     
       11. The anisotropic polyamide dope of claim 7, wherein said inorganic salt is selected from the group consisting of CaCl 2 , LiCl, NaCl, KCl, LiBr and KBr. 
     
     
       12. The anisotropic polyamide dope of claim 7, comprising 7 to 23% by weight of said aromatic polyamide. 
     
     
       13. The anisotropic polyamide dope of claim 7, comprising 1 to 10% by weight of said inorganic salt. 
     
     
       14. The anisotropic polyamide dope of claim 7, wherein said polar organic solvent is selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, hexamethyl phosphoamide, N,N,N',N'-tetramethyl urea, N,N-dimethyl formamide and dimethyl sulfoxide. 
     
     
       15. An article selected from the group consisting of a fiber, pulp and a film produced by a process comprising spinning and coagulating the anisotropic polyamide dope of claim 7. 
     
     
       16. The article of claim 15, having a tensile strength of at least 10 g/d. 
     
     
       17. The article of claim 15, having a tensile modulus of at least 450 g/d. 
     
     
       18. A process of making an optical anisotropic polyamide dope, comprising: (a) adding and dissolving an aromatic diamine having a nitrile group substituted on the aromatic nucleus in an organic solvent, where said solvent is an amide or a urea;   (b) adding pyridine to the solution from step (a);   (c) adding an aromatic diacid halide to the solution from step (b) with vigorous stirring at a temperature of 0°-50° C.; and   (d) stirring the solution from step (c) for 1 to 360 minutes to obtain a viscous polymer solution which shows silver-white brightness when stirred.   
     
     
       19. The process of claim 18, wherein said aromatic diamine is selected from the group consisting of ##STR16## wherein Y is Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms. 
     
     
       20. The process of claim 18, wherein said aromatic diacid halide is selected from the group consisting of terephthalic chloride, isophthalic chloride and diphenyl chloride, which may be unsubstituted or substituted with Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms. 
     
     
       21. The process of claim 18, wherein said organic solvent is selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, hexamethyl phosphoamide, N,N,N'N'-tetramethyl urea, N,N-dimethyl formamide and dimethyl sulfoxide. 
     
     
       22. The process of claim 18, wherein said organic solvent contains an inorganic salt. 
     
     
       23. The process of claim 22, wherein said inorganic salt is selected from the group consisting of CaCl 2 , LiCl, NaCl, KCl, LiBr and KBr. 
     
     
       24. The process of claim 22, wherein the amount of said inorganic salt is less than 12% by weight of said organic solvent. 
     
     
       25. A process of making an optical anisotropic polyamide dope, comprising: (a) adding and dissolving an aromatic diamine having a nitrile group substituted on the aromatic nucleus in an organic solvent, wherein said solvent is an amide or a urea;   (b) adding an aromatic diacid halide to the solution from step (a) with vigorous stirring at a temperature of 0°-50° C. to produce a gel polymer;   (c) keeping the mixture from step (b) for 0-24 hours; and   (d) adding and dissolving at least one inorganic alkali compound.   
     
     
       26. The process of claim 25, wherein said aromatic diamine is selected from the group consisting of ##STR17## wherein Y is Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms. 
     
     
       27. The process of claim 25, wherein said aromatic diacid halide is selected from the group consisting of terephthalic chloride, isophthalic chloride and diphenyl chloride, which may be unsubstituted or substituted with Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms. 
     
     
       28. The process of claim 25, wherein said organic solvent is selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, hexamethyl phosphoamide, N,N,N',N'-tetramethyl urea, N,N-dimethyl formamide and dimethyl sulfoxide. 
     
     
       29. The process of claim 25, wherein said inorganic alkali compound is selected from the group consisting of Li 2  CO 3 , CACO 3 , LiH, CaH 2 , LiOH, Ca(OH) 2 , Li 2  O and CaO. 
     
     
       30. A process for preparing an optical anisotropic polymer dope, comprising: adding an aromatic polyamide of formula (I) ##STR18##  to a polar organic solvent containing therein at 1% by weight or more of an inorganic salt at a temperature of 0°-100° C.,   wherein the dope contains at least 7% by weight of said aromatic polyamide;   R is an aromatic group having a nitrile group substituted on the aromatic nucleus or an aromatic group that does not have a nitrile group substituted on the aromatic nucleus, where at least 25 mol % of R is an aromatic group having a nitrile group substituted on the aromatic nucleus;   R' is phenyl, napthyl or diphenyl, which is unsubstituted or substituted with Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms; and   n is an integer between 10 and 100,000.   
     
     
       31. The process of claim 30, wherein R is selected from the group consisting of ##STR19## where Y is Cl, Br, I, NO 2 , an alkyl group having one to four carbon atoms or an alkoxy group having one to four carbon atoms. 
     
     
       32. The process of claim 30, wherein 100 mol % of R is an aromatic group having a nitrile group substituted on the aromatic nucleus. 
     
     
       33. The process of claim 30, wherein said aromatic polyamide has an intrinsic viscosity of at least 2.0. 
     
     
       34. The process of claim 30, wherein the dope contains 7-23% by weight of said aromatic polyamide. 
     
     
       35. The process of claim 30, wherein the dope contains 1-10% by weight of said inorganic salt. 
     
     
       36. The process of claim 30, wherein said inorganic salt is selected from the group consisting of CaCl 2 , LiCl, NaCl, KCl, LiBr and KBr.